Wi-Fi has become the dominant means for indoor wireless communications. Because Wi-Fi is so ubiquitous and steadily increasing in bandwidth, users assume that Wi-Fi will soon become the means for Gigabit indoor wireless communications as well. This may be true eventually to a limited extent, but not much beyond a few Gigabits for quite some time. And the expectation of ‘wireless everywhere’ will become less likely as Wi-Fi bandwidths are pushed upwards because higher frequencies (ie-microwaves) propagate best in beams and not omni-directionally.

In the meantime, the volume and size of data files continues to increase exponentially while Wi-Fi bandwidth increases are linear at best and slowing down at worst. Wi-Fi bandwidths are compatible with streaming applications but not for fast transfer of large blocks of data such as HDTV movies recorded on PVRs, camcorders or even smartphones.

Bandwidth scalability of Wi-Fi is now usually done by simply adding transceivers and antennas, each of them consuming more bandwidth. This game soon runs out of available spectrum unless you are willing to use the not-yet-developed millimeter microwave frequencies (ie-60GHz 802.11ad), which must be ‘beamed’.

Have you ever tried to back-up your computer via 802.11n Wi-Fi? The process is lengthy and prone to crashes. With more data being stored remotely on devices elsewhere in the building or in the cloud, fast bi-directional access remains a major problem for indoor wireless users.

This “bandwidth gap” will continue to widen between what is desired and what is practicable. This provides other technologies, particularly gigabit infrared (IR) optical wireless (herein called “Li-Fi”), with a deep and enduring opportunity to deliver performance where Wi-Fi falls short.

Li-Fi (IR) versus Wi-Fi (RF)

Li-Fi is poised to be a powerful alternative to Wi-Fi solutions for indoor wireless communications at data rates of 5 Gigabits/second and up. Li-Fi is likely to be far more scalable than Wi-Fi for bandwidths into tens of Gigabits and well beyond. There are several options for increasing high-speed optical modulation and detection, whereas implementing higher Wi-Fi bandwidth rapidly becomes more problematic as the base-band frequency increases. The physical nature of Wi-Fi delivers diminishing data rate returns on increases in base band frequencies.

During the last few years, the use of Wi-Fi in public places such as the classroom has been a controversial issue in the international media. Public and government concerns (see EU, Canada and Israel, etc.) have been raised due to alleged health issues. Li-Fi technology can put the minds of millions of concerned users at ease. The only health concern connected with Li-Fi is the laser eye-safety issue, which is far more easily handled than the RF exposure of gigabit Wi-Fi. A sheet of paper can stop optical beams while Wi-Fi penetrates walls and bodies. This factor is not only a perceived health issue, but also touches upon security.

Li-Fi is more secure than Wi-Fi because optical beams are very difficult to hack without detection. It is simpler because it does not require any spectrum license. It is versatile because the beam will not interfere with electronics or with other beams. Because multiple optical channels can be beamed as a parallel bundle and can easily be kept separate, increased channel capacity can be linearly scaled unlike Wi-Fi. Bandwidth can be further scaled by using different wavelengths and by modulating the optical signal with digital amplitude modulation. Unlike Gigabit Wi-Fi, Li-Fi beams can easily be spread and shaped into almost any format. This enables a broadcast model, which can be shared by many users in a variety of ways.

Challenges

Optical transmitters must be physically pointed towards the receiver, but this can be handled with multiple transmitter/receiver sets in the optical module. Optical receivers have a more limited “acceptance angle” than Wi-Fi, but this is overcome with better collection optics derived from solar concentrator panel technologies. Wi-Fi´s weakness regarding security (penetration of walls and bodies) could be a qualified advantage in that it allows multi-room use and minimizes line-of-sight issues. On the other hand, the “spectrum reusability” of Li-Fi in adjacent rooms can be used to advantage. Wi-Fi technologies will be integrated entirely on a single CMOS chip, but much of the optical module electronics could be integrated as well. Wi-Fi implementations for ranges beyond close docking can be implemented with smaller apertures than optical. However, more efficient high-speed IR-detectors can reduce the required optical power and thereby allow smaller apertures to meet Class 1 laser safety criteria.

Opportunities

The multi-gigabit precedents set by interfaces including USB 3.0, PCIe, Thunderbolt, eSATA, 10G SFP+ and HDMI create a rich set of “sockets”. Users have a high bias towards wireless solutions, and this will especially be true for the optical gigabit class of interface. Li-Fi represents the leading edge of wireless communications progress. Light has the connotation of being the fastest medium on our planet, which is a psychological advantage of optical technology. This is why Li-Fi for communications is often perceived as superior to RF. In addition, Li-Fi can provide a more durable and survivable connection by eliminating the inevitable damage that can happen to delicate gigabit cables. Li-Fi can also be used in gigabit applications where cables are unfeasible because they require electrical isolation due to concerns over RFI, high voltage, dangerous chemicals or radiation. The flexibility of making gigabit links without having to plug in or string cables will make it attractive for temporary or interchangeable system setups.

But the true value of Li-Fi will be to open up entirely new usage models. The initial applications will likely be docking (<1cm), board-board links (1-3cm) kiosks (10-20cm), and beaming (1-10m); not necessarily in that sequence.

The “lowest-hanging fruit” for taking advantage of Li-Fi will likely be for a pair of point-to-point optical wireless boxes (about the size of tiny Bose speaker cubes) for commercial applications such as server farms, public facilities (think stadiums, auditoriums, theaters, expo halls, airports, etc.), high-data roll-around devices (think medical instruments and industrial diagnostic systems) and open-format offices. The most likely cabled interfaces to these boxes would be 10G SFP+ fiber and USB 3.0 because of the ubiquity of the sockets, the fact that they are symmetric bi-directional, and that the implementations are technically the simplest of all the interfaces. These applications will be driven not by price or package size but by performance. This will give great flexibility to creating these products using off-the-shelf components rather than requiring high levels of integration.

For computers and mobile electronics, most new “add-on” features (e.g. Wi-Fi & BlueTooth) were first introduced as a plug-in module and only later were integrated within the body of the product once widespread adoption was assured. Li-Fi interfaces will likely follow this path as well. External modules or “dongles” will always have more flexibility in terms of package size than internal implementations.

The performance and utilitarian advantages of Li-Fi are so profound that early adoption for portable devices might prove to be a very smart strategic move for OEMs. Given the diversity of applications, Li-Fi has the potential to grow quickly across the wireless industry as a new wireless ecosystem while taking the user experience to new levels. Manufacturers of mobile and high data content devices such as mobile phones, tablets, laptops, digital cameras, camcorders, hard-drives and even flash memory drives will be able to brand their names as leaders within this emerging market. One fact is for sure; Li-Fi is emerging, and it will take many shapes. All of them are inter-connectable. As is so often the case, it is just a matter of who arrives first with the most compelling products to take the industry lead. In all these applications, Li-Fi is able to transfer data of massive amounts in very high rates. Just imagine: You download several 10 Gigabyte HDTV 3D movies into a tiny flash drive in a matter of seconds, and then play them back on any USB 2 device at your leisure.

This is just the tip of the iceberg of new possibilities with Li-Fi.

About the Author

Rudi Wiedemann is the Managing Partner for Technology Vendors at IBSENtelecom. He is a technology- marketing expert specializing in matching Li-Fi solution architectures to compelling new usage models. He currently leads the IrDA Working Group for the new 10GigaIR interface standard. He has been an executive for over 30 years in the laser, optics and imaging fields. Contact him at rudi@ibsentelecom.no

About IBSENtelecom

IBSENtelecom specializes in promoting and developing compelling new Li-Fi solutions. We work closely with OEMs to develop usage models and product specifications that fit into their product roadmap. We work closely with leading technology vendors that provide chips, software, engineering services and technology licenses to a project. We match these technologies to the OEM’s design objectives to achieve the best overall price, package and performance according to their needs. We manage this process to ensure smooth progress from concept to delivery.